A perculiar find

Today I took a different route out on the Forvie dunes, the light was failing as I sprinted across , weaving my way around the peaks and troughs of the sand dunes to reach the sea before dark. I was hoping for some wild life on the beach but instead found this peculiar thing, lots of spheres stuck together in a chalk thing, each with a glassy blob in the middle. 

If anyone can guess what it is I would be interested!